System for controlling web tension



y 1969 H. R. WILCOX SYSTEM FOR CONTROLLING WEB TENSION Sheet Filed Aug.22, 1967 FIG.|

AIR SUPPLY AIR ACTUATE BRAKE OR CLUTCH FIG. 2

I INVENTOR. HAROLD R. WILCOX BY 0710M m @JI ATTORNEYS May 27, 1969 H. R.WILCOX Filed Aug. 22, 1967 Sheet 2 012 BRAKE To 64 CLUTCH F I G. 3

\REG. V

INVE NTOR. FIG 4 HAROLD R. WILCOX ATTORNEYS 3,446,451 SYSTEM FORCONTROLLING WEB TENSION Harold R. Wilcox, Maynard, Mass., assignor toRiggs & Lombard, Inc., Lowell, Mass, a corporation of MassachusettsFiled Aug. 22, 1967, Ser. No. 662,334 Int. Cl. B65h 77/00 US. Cl.24275.43 10 Claims ABSTRACT OF THE DISCLOSURE A beam carries a tensiondetecting roller to actuate a ball valve also carried by the beam. Thevalve is connected to a clutch or brake which controls a roller inengagement with the web. As the tension changes, the beam is movedcausing the valve to be actuated and vary the braking or clutchingaction.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to web control systems and more particularly isdirected towards a new and improved system for maintaining a uniformlongitudinal tension on a moving web.

Description of the prior art There are a great many processes andapparatus which involve a running web where it is desirable to maintaina constant and uniform longitudinal tension On the web as it movesalong. For example, in the manufacture of textiles maintenance of webtension is important at various stages of production. Various mechanismshave been developed heretofore for the purpose of controlling the webtension in a predetermined manner. Systems presently available have beenfound to be generally unsatisfactory for one reason or another. Forexample, most systems are highly complicated installations involving agreat many interacting components all of which must be working perfectlyfor the system to operate as intended. Generally, systems of this typeare highly expensive and because of their complexity tend to beunreliable particularly for long periods of operation. Furthermore,systems presently available are not readily adjustable to accommodatedifferent types of webs. It is therefore an object of the presentinvention to provide a new and improved system for controllinglongitudinal tension on a moving web and one which is of a simple,low-cost construction and which is readily adjustable.

Summary of the invention This invention features a system forcontrolling web tension comprising a roller mounted on a resilient beamand engaging the moving web. The beam carries a movable nozzle elementwhich is connected to the air supply for an air-actuated clutch orbrake. The movable nozzle is provided with a valve element which ispositioned by means of a screw adjusting device mounted on a fixedportion of the frame whereby manipulation of the screw adjusting devicepreloads the beam and allows the valve to bleed air from the system whenthe web tension reaches a predetermined level. As the web tensionincreases the valve opens and bleeds air from the air system. This inturn modifies the action of the air brake or clutch which in turncorrects the web tension.

Brief description of the drawings FIG. 1 is a partially sectional viewin side elevation and somewhat diagrammatic view of a web tensioncontrol system made according to the invention,

FIG. 2 is a detail view in end elevation thereof,

nited States Patent 3,446,451 Patented May 27, 1969 FIG. 3 is a somewhatdiagrammatic view in perspective showing a modification of the system,and,

FIG. 4 is a top plan view, also somewhat digrammatic, showing a furthermodification of the invention.

Description of the preferred embodiments Referring now to FIGS. 1 and 2of the drawings, the reference character 10 generally indicates a movingweb running about a tension detecting roller 12 and thence to a secondroller 14 which may be a take-up roller for winding up the web 10 or adriven roller for advancing the web further along. In either event, theroller 14 is drivingly connected to an air-actuated speed control devicesuch as a slip clutch or brake depending upon the particularapplication. The air-actuated device 16 is connected via a conduit 18 toa source of compressed air with a pressure regulator 20, a gauge 22 anda needle valve 24 being located in the line. Typically the unit 16 willoperate at 60 psi. for which will be set on the pressure regulator 20and the needle valve will be set to pass 1 c.f.rn. of air whenoperating. These values are only typical and obviously may be variedaccording to the specific requirements.

The tension detector web roller 12 is supported at its ends by means ofbearings 26 one of which bearings is mounted in turn upon a resilientsupport generally indicated by reference character 28. The resilientsupport includes a beam arm 30 on the upper surface of which is mountedthe bearing 26 and which beam arm extends out from a spacing block 32.The block in turn is fastened to a parallel beam 34 fixed to a mountingstand 36. The block 32 is located off to the side of the vertical centerline of the roller and insofar as the beam arm 30 is of a slightlyresilient material, such as steel, it will deflect to a certain extentupon the application of a load to the roller 12 as occasioned by tensionon the web 10. Typically deflection of the beam will be on the order of.O08"-.0O9".

Carried on the outer end of the beam arm 30 is a nozzle 40 which isconnected by a flexible conduit 42 to the conduit 18 which delivers airto the air-actuated device 16. The conduit 42 serves as a bleeder linefor the system with the air being delivered into the nozzle at inletopening 44 and out of the nozzle through an outlet port 46 formed at thebase of a conical valve seat 48 formed in the upper face of the nozzle.Trapped in the conical Seat 48 of the nozzle is a ball element 50 whichis held by means of an overhead screw 52 threaded through a fixedbracket 54 mounted on the lower fixed beam 34. The screw 52 is providedwith a locking nut 56 for locking the screw in a selected position.

With the screw holding the ball fully down against the valve seat thenozzle will be shut off and no air will escape from the bleeding line42. Under these conditions the air being delivered to the air-actuateddevice 16 will remain constant and the system will be stable. Assumingthat for one reason or another, the tension on the web 10 changes. Anincrease in the web tension will place a greater load on the tensiondetecting roller 12 and will cause the beam 30 to deflect downwardly.This movement of the beam 30 will cause the nozzle 40 to drop down to anextent corresponding to the movement of the roller 12 and the beam 30.When the nozzle drops down the air in the bleeder line 42 will bereleased past the ball element 50, this in turn creating a drop in thepressure in the main air line 18. The decrease in the pressure to theair-actuated unit 16 will cause a reduction in the braking or clutchingaction imparted to the roller 14 and this, in turn, will decrease thetension on the web 10. As the web tension decreases the beam 30 willrise reducing the amount of air escaping from the nozzle 40 or shuttingit off altogether depending upon the amount of correction that takesplace in the web tension. In any event, the system will return to astable condition and the tension on the web will be maintained. Inpractice, the response is extremely fast and once the tension has beenset it will normally remain constant with corrections taking placeautomatically.

The use of the resilient beam along with a simple flow control valveminimizes air loss and the ball relief type of valve attached directlyto the beam has the further advantage in that with the screw adjustmenton top to clamp down the ball it is possible to pre-stress the beam andallow the ball valve to bleed only when additional tension occurs on thecloth or web.

The single air line 18 connects with the air-actuated device 16 whichtypically may be either a disc type of brake or a slip clutch dependingupon whether the system is being used in an arrangement for controllingthe tension in a brake type of let-off unit or whether it is in use tocontrol tension in the case of rolling up a web. The system has manyother uses. For example, for controlling the tension in a let-off unitit may be connected with an air brake. For a centerline type of roll-upor a surface type of roll-up the air pressure to a slip clutch may becontrolled in order to maintain a constant controlled tension on theweb.

Another use of the system would be in connection with a closed vesselusing a fixed shaft with a roll mounted on the fixed shaft. The shaftmay be sealed within the sides of the vessel and a sensor of the typedisclosed above located on the outside of the unit. The roll can thenrotate on the shaft itself within the unit.

In certain applications, as in the textile industry, it is commonpractice to unroll the web from. one roll onto another and then reversethe direction of the web to rewind the web back onto its original roll.In such applications it is desirable to utilize the slip type of clutchon a specific roll when rolling up and likewise to use an air brake onthe same roll when the fabric is being pulled off of this particularroll. Such a system is shown in FIG. 3. In FIG. 3 the referencecharacter 60 indicates a feed roll and reference 62 indicates a take-uproll with the reference character 64 indicating a web passing over a webtension roller 66 mounted in the manner disclosed in FIGS. 1 and 2. Asshown in FIG. 3 the take-up roll 62 is operatively connected to anair-actuated slip clutch 68 at one end and an air brake 70 at theopposite end. The units 68 and 70 are provided with conduits 72, 74, 76and 78 which connect with a solenoid actuated four-way valve 80. Thevalve 80, in turn, to a source of compressed air. As in the principalembodiment a bleeding line 84 connects with the main line 82 and to aresilient beam actuated nozzle relief valve 86 of the same type as inFIGS. 1 and 2.

The conduits 72 and 78 are bleeding lines which are kept open wheneither of the units 68 or 70 is inoperative. Depending upon whichdirection the web 64 is moving the solenoid actuated valve 80 will beshifted to one side or the other to actuate either the clutch or thebrake. In winding up a web, the clutch 68 will be employed and thefour-way valve will be in the position shown in FIG. 3. This willactuate the clutch and will at the same time bleed air from the brake70. When the web is being moved in the reverse direction the valve willbe shifted to cut off the clutch and deliver air to the brake 70 withthe bleeding line from the clutch being open.

Referring now more particularly to FIG. 4 there is shown anothermodification of the invention and in this embodiment the web tensionsystem is employed in a range drive arrangement. In FIG. 4 a rangecomprising a series of drive rolls 90 and 92 mounted on a frame 94 isdriven by a common drive shaft 96 running along the length of the range.The shaft 96 is drivingly connected to a motor 98 or the like and isemployed to transmit driving power to the individual rolls 90 and 92 asthrough bevel gearing 100. Each roller 90, etc., is provided with an isconnected via a conduit 82 air clutch 102 of the slip type with each airclutch operatively connected to a common air supply line 104 by means ofa branch line 106. Connected to each branch line is a bleeder line 108connected to a resilient beam bleeding valve 110 of the sort disclosedin FIGS. 1 and 2. Each valve is operatively connected to a web tensiondetecting roller 112 and functions in the same manner as in theprincipal embodiment. The individual sensors are used for controllingthe air pressure to the individual slip clutches so that the web may berun through the machine in a synchronized condition.

While the web tensioning system has been disclosed with respect todifferent specific applications, numerous other applications will appearto those skilled in the art.

Having thus described the invention, what I claim and desire to obtainby Letters Patents of the United States is:

1. A system for controlling web tension, comprising (a) a web-engagingmember about which said web travels,

(b) a fixed frame,

(c) a resilient beam mounted at one end to said frame and supportingsaid member,

(d) a valve having a movable portion carried by said beam and a fixedportion mounted to said frame,

(e) said valve being adapted to open and close upon deflection of saidbeam in response to changes in web tension,

(f) a pressure responsive fluid actuated device for controlling thespeed of said web,

(g) means supplying pressurized fluid to said device and,

(h) a conduit connecting said valve to said means to vary said pressureupon actuation of said valve.

2. A system according to claim 1 wherein said web-engaging member is aroller.

3. A system according to claim 1 wherein said valve includes a ballelement trapped between the fixed and movable portions of said valve anda screw threaded through said fixed portion of the frame and engagingsaid ball element.

4. A system according to claim 1 wherein said fluid actuated device is abrake.

5. A system according to claim 1 wherein said fluid actuated device is aclutch.

6. A system for controlling web tension, comprising (a) a first rollhaving a length of web wound thereon,

(b) a second roll spaced from said first roll and adapted to wind theweb from said first roll,

(0) a pressure responsive fluid actuated clutch operatively connected tosaid second roll,

(d) a pressure responsive fluid actuated brake operatively connected toone of said rolls,

(e) a multi-position valve connecting said clutch and brake,

(f) control means for operating said multi-position valve forselectively actuating said brake or said clutch,

(g) a pressure relief valve operatively connected to said multi-positionvalve,

(h) a resilient beam supporting a portion of said relief valve inoperative relation to a fixed portion of said relief valve,

(i) web engaging means carried by said beam and adapted to bias saidbeam and operate said relief valve in response to tension in said web,

(j) operation of said relief valve adapted to alter the pressure to saidbrake and clutch to maintain tension on said web.

7. A system according to claim 6 wherein said web engaging means is aroller.

8. A system for controlling the tension on a web moving through a rangecomprising,

(a) a plurality of rollers drivingly engaging said web,

(b) a common drive source for rotating said rollers,

(c) a pressure-responsive fluid-actuated speed control 5 deviceoperatively connected between said source and each of said rollers,

(d) a pressure relief valve for each roller and operatively connected toeach device,

(e) means responsive to changes in web tension for actuating said valvewhereby pressure at each device will be controlled to maintain tensionon said web through said range.

9. A system according to claim 8 wherein said means includes a webengagingmember and a resilient beam supporting said member and fixed tosaid range, said beam supporting one portion of said valve portinganother portion whereby movement of said memand said range supber andbeam in response to web tension will actuate said valve.

10. A system according to claim 9 wherein said member is a roller.

5 References Cited UNITED STATES PATENTS 954,089 4/1910 Goss 242-75.432,261,891 11/1941 Stewart 242-7543 10 3,330,457 7/1967 Poster et al24275.43 X

NATHAN L. MINTZ, Primary Examiner.

